Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
  • C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
  • C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
  • C07D277/32—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D277/56—Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen

Definitions

• the present invention relates to a novel process for preparing 2-aminomethyl-4-cyanothiazole.
• the key step of the synthesis sequence is the construction of the thiazole ring.
• the thiazole ring is obtained by reacting a thioamide with a bromopyruvic acid derivative (1) G. Videnov, D. Kaiser, C. Kempter, G. Jung, Angew. Chem. Int. Ed. Engl. 35 (1996), 1503; (2) Y. Nakamura, C. Shin, K. Umemura, J. Yoshimura, Chem. Lett. (1992), 1005; (3) J. A. Sowinski, P. L. Toogwood, J. Org. Chem. 61 (1996), 7671; (4) M. North, G. Pattenden, Tetrahedron 46 (1990), 8267; (5) U. Schmidt, Synthesis 1987, 233; (6) WO 98/6741.
• the thioamides used for this purpose are obtained, for example, by reacting an amide with Lawessons' reagent (1), (2), (3), or by reacting an aminonitrile with H 2 S (7) K. P. Moder, F. R. Busch, D. C. Richter, Org. Prep. Proced. Int. 24 (1992), 66; G. Li, P. M. Warner, D. J. Jebaratnam, J. Org. Chem. 61 (1961), 778; T. P. Holler, F. Q. Ruan, A. Spaltenstein, P. B. Hopkins, J. Org. Chem. 54 (1989), 4570; T. P . Culbertson, J. M. Dornagala, P.
• 2-aminomethyl-4-cyanothiazole would be an interesting intermediate for preparing serine protease inhibiting low-molecular-weight substances (for example thrombin inhibitors).
• thrombin inhibitors are mentioned, for example, in WO 9806741.
• 2-aminomethyl-4-cyanothiazole can be used for preparing other thrombin inhibitors and their prodrugs such as, for example, N-(ethoxycarbonylmethytene)-(D)cyclohexylaianyl-3,4-dehydro-prolyl-[2-(4-hydroxyamidino)thiazole]methylamide hydrochloride.
• R 1 is branched or straight-chain C 1 -C 10 -alkyl or
• R 2 is branched or straight-chain C 1 -C 10 -alkyl or C 1 -C 4 -alkoxy or C 1 -C 4 -dialkylamino.
• Preferred substituents are —OCH 3 , OCH 2 CH 3 , N(CH 3 ) 2 , N(C 2 H 5 ) 2 , CH 3 , C 2 H 5 , C 3 H 7 .
• the thiazole ring is obtained by reacting an aminonitrile with L-cysteine, giving the thiazolidine, followed by its oxidative aromatization.
• thiazolidine syntheses are known where the thiazolidine is obtained by reacting the cysteine derivative with imido esters (3), (4), (10), (13) K. Inami, T. Shiba, Bull. Chem. Soc. Jpn. 58 (1985), 352.
• imido esters are likewise not commercially available and have to be synthesized by a multi-step process, for example from an aminonitrile.
• the thiazolidine was synthesized from an aminonitrile, with quantitative conversion.
• the reaction of the cysteine ester hydrochlorides, in particular the methyl and ethyl esters, with the protected aminoacetonitrile is carried out in an inert solvent, for example in cyclic or open-chain ethers, such as THF, dioxane, DME, in acetonitrile, DMF, or chlorinated hydrocarbons such as CH 2 Cl 2 , CHCl 3 or in toluene, or in an alcoholic medium (C 1 -C 6 -alcohol, preferably isopropanol, ethanol or methanol) in the presence of a base, such as, for example, NEt 3 , morpholine, pyridine, lutidine, DMAP, DBU, DBN (preferably triethylamine).
• a base such as, for example, NEt 3 , morpholine, pyridine, lutidine, D
• the thiazolidine can then be oxidized quantitatively to the corresponding thiazole.
• the oxidation is likewise carried out in inert solvents, such as, for example, chlorinated hydrocarbons, toluene or cyclic and open-chain ethers.
• Organic amines such as NEt 3 , morpholine, pyridine, DMAP (dimethylaminopyridine) and lutidine serve as base.
• the next step in the synthesis sequence according to the invention is the aminolysis of the ester to give the amide.
• the aminolysis can be carried out both in aqueous medium and in alcoholic ammonia solution. It is possible to use alcoholic NH 3 solutions (for example in MeOH, EtOH, iPrOH), but also aqueous NH 3 solutions (for example 25% strength).
• the process according to the invention is characterized in that the reaction can be carried out in highly concentrated form using the crude thiazolecarboxylic acid ester. If the process is carried out on an industrial scale, this results in a good space-time yield.
• the conversion into the 2-aminomethyl-4-cyanothiazole (VIII) or (Ia) and (Ib) can then be carried out in a simple manner by dehydratization using, for example, trifluoroacetic anhydride, and subsequent gentle removal of the BOC protective group.
• the process according to the invention is characterized in that it can be carried out in a simple manner, without costly purification. All the essential reaction steps proceed with quantitative or almost quantitative yields. The costs of the starting materials are low, and the use of toxic substances (in particular gases) can be dispensed with.
• the thiazolecarboxylic acid ester can be obtained in crystalline form.
• hydrolyzing the ester with, for example, aqueous sodium hydroxide solution, followed by pH-controlled addition of acid it is also possible to prepare in a simple manner and with good yields the corresponding BOC-protected thiazolecarboxylic acid by this route.
• the present invention relates to a process for preparing 2-aminomethyl-4-cyanothiazole and its salts of the formulae Ia and Ib
• n 1 or 2
• X is chloride, bromide, triflate and hydrogen sulfate and
• the 4-cyanothiazoles VII and VIII are novel.
• the intermediates IV and V can be converted advantageously, without further work-up, into the respective subsequent product.
• the 4-cyanothiazole salt VIII which is embraced by the formula Ia, can be reacted under pH-controlled conditions with bases to give the salt-free form of the formula Ib.
• the invention furthermore relates to processes for preparing 2-aminomethyl-4-cyanothiazole and its salts of the formulae Ia and Ib
• n 1 or 2
• X is chloride, bromide, triflate and hydrogen sulfate and,
• R 1 is branched or linear C 1-10 -alkyl or
• n 0, 1 or 2 and R 2 is branched or straight-chain C 1 -C 10 -alkyl or C 1 -C 4 -alkoxy or C 1 -C 4 -dialkylamino, in an inert solvent in the presence of a base at from 0° C. to 80° C. until the reaction has essentially proceeded to completion.
• the cysteine ester is preferably present as hydrochloride.
• R 1 is as defined above is stirred in an alcohol R 2 OH, in which R 2 is branched or linear C 1-8 -alkyl, HO—CH 2 —CH 2 —, HO—CH 2 —CH 2 —CH 2 — or C 1-4 -alkyl-O—CH 2 —CH 2 —, at from 0° C. to 40° C. with from 1 to 50 molar equivalents of NH 3 until the reaction has essentially proceeded to completion.
• the invention relates to a process for preparing the compound of the formula V
• R 1 is branched or linear C 1-10 -alkyl or
• n 0, 1 or 2 and R 2 is branched or straight-chain C 1 -C 10 -alkyl or C 1 -C 4 -alkoxy or C 1 -C 4 -dialkylamino in an inert solvent in the presence of a base at from 0° C. to 80° C. until the reaction has essentially proceeded to completion.
• R 1 is as defined above is stirred in an alcohol R 2 OH at from 0° C. to 40° C. with from 1 to 50 molar equivalents of NH 3 in an aqueous ammonia solution until the reaction has essentially gone to completion.
• n 1 or 2
• X is chloride, bromide, triflate and hydrogen sulfate and
• 2-Aminomethyl-4-cyanothiazole hydrochloride 64 g, 364 mmol was added to a solution of BOC-3,4-dehydroproline (77.5 g, 349 mmol) in methylene chloride (150 ml).
• diisopropylethylamine 157 g, 1.2 mol was added dropwise with stirring to the suspension.
• propanephosphonic acid anhydride 50% strength in ethyl acetate, 290 g, 456 mmol
• the reaction mixture was warmed to 20° C., and 240 ml of methylene chloride and then 310 ml of water were added.
• the organic phase was separated off, the aqueous phase was washed with 200 ml of methylene chloride and the organic phases were combined.
• the collected organic phases were admixed with 200 ml of water and the pH was adjusted to pH 3 using conc. hydrochloric acid.
• the organic phase was separated off again and then washed with 200 ml of water.
• the solvent of the organic phase was distilled off and the residue was taken up in 860 ml of isopropanol.
• N-(tert-butoxycarbonylmethylene)-(BOC)-(D)-cyclohexylalanyl-3,4-dehydroprolyl-[2-(4-cyano)thiazole]methylamide (22.2 g, 36.7 mmol) was dissolved in ethanol (250 ml), the solution was admixed with hydroxylamine hydrochloride (6.41 g, 92.2 mmol) and diisopropylethylamine (23.8 g, 31.6 ml, 184.5 mmol) was slowly added dropwise with cooling (water bath) to this suspension.
• the reaction solution was concentrated under reduced pressure using a rotary evaporator, the residue was taken up in methylene chloride/water and the aqueous phase was adjusted to pH 3 using 2N hydrochloric acid and extracted. The organic phase was washed repeatedly with water, dried over magnesium sulfate and concentrated under reduced pressure using a rotary evaporator. The residue was triturated with n-hexane, giving 22.5 g of the title compound as an almost pure white solid.
• N-(tert-butoxycarbonylmethylene)-(BOC)-(D)-cyclohexylalanyl-3,4-dehydroprolyl-[2-(4-hydroxyamidino)thiazole]methylamide (2.0 g, 3.15 mmol) was dissolved in ethanol (25 ml), and the solution was admixed with 10 ml of 5N hydrochloric acid in ether and stirred at 60° C. for 3 h.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Thiazole And Isothizaole Compounds (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Plural Heterocyclic Compounds (AREA)

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Citations (2)

• 1999
  • 1999-07-23 DE DE19934066A patent/DE19934066A1/de not_active Withdrawn
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